Uncount nouns used as count nouns:
coffee, cheese, wine, food, are uncount nouns (Do you want some coffee?)
but they can be used as count noun: (I’d like a coffee)
a coffee : a cup of coffee, a kind of coffee, a type of coffee, etc …
Nouns have two forms: count / uncount form:
HOPE vs HOPES:
Keep always hope in yourself / I have hopes to see her tonight.
TRAVEL vs TRAVELS:
Travel can teach you a lot. / How many travels did you do last year?
Nouns have two meanings: a count / uncount meaning:
danger (generality) and a danger of something, (fire, …),
language (linguistic, generality) and to study a language (english language, …),
paper (substance, made of paper) and « a paper » (a magazine),
Business, (/ my own business), Time, (/a good time), Death, (/one’s death), Use (/many uses),etc …
Uncount nouns that end in -s (-s = end of a plural count form):
Economics, mathematics, physics, … Economics is interesting,
gymnastics, athletics, … Athletics is tiring,
billiards, cards, darts, … Billiards is easy to play,
Group nouns: A group noun refer to many people, and can be used as a singular noun!
There are nouns as public, team, group, that refer to groups of people (or things), BUT …
but we can use them either as singular nouns … either as plural nouns. [Oh my god !!] Ex: company, crew, family, gang, group, staff, team, army, regiment, enemy, government, audience, committee, public, media, flock, herd, etc …
Group noun as a single person/thing:
The group is homogene.
The audience makes its decision.
Group noun as a union of several people/things:
The better group are the americans.
The audience clapped their hands.
Group noun either as a singular nouns, either as plural nouns:
My family is funny. (family = one group, one thing)
My family are grand-parents, uncles, aunts and 5 cousins. (family = different members).
About crew, staff, organisations, group … there are used as a plural noun when we speak.
Two Part-nouns: Things that have … ??? … two parts!
Shorts, jeans, pyjamas, trousers, pants, trainers, shoes, glasses, spectacles, scissors, pliers, pincers, knickers, tweezers, tights, …
We use « a pair of xxx » if we want to refer to one item: A pair of shoes/trousers/glasses …
We use « pairs of xxx » if we want to refer to many items: I’ve got six pairs of jeans.